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April 6, 2000

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.


Kulanaokuaiki campground: a whole lot of shaking going on

On March 31, Hawai`i Volcanoes National Park officially opened Kulanaokuaiki campground, a barrier-free facility along the Hilina Pali Road south of Kilauea's caldera. The new campground replaces the Kipuka Nene picnic area, 2 km (1.2 miles) farther southwest, which is now closed to protect Hawai`i's state bird. Kulanaokuaiki campground occupies a dynamic landscape controlled by Kilauea's eruptive and faulting history.

The name tells a lot about the area. Kulanaokuaiki means "the shaking of a small spine [or sharp ridge]." The campground is just north of the 15-m-high (50-foot-high) pali that bears its name. This pali is an earthquake fault, formed by vertical ground movement during periods of intense shaking. Imagine people on top of the pali during an earthquake. Rocks would crash from the face of the pali to the ground below, and the pali would tremble from one shock after another during a swarm of earthquakes.

Such an earthquake swarm took place 35 years ago. On Christmas Eve and Day in 1965, strong shaking and faulting broke the Hilina Pali Road, where it crosses Kulanaokuaiki Pali near the new campground. The pavement was offset vertically 2.6 m (8.4 feet). The campground side of the fault went down 1.8 m (6 feet), and the other side (the south side) went up 0.8 m (2.4 feet). During the swarm, a truck from HVO carrying portable seismic equipment was parked near the broken road when it was nearly toppled by a large earthquake.

Hundreds of other faults and cracks north and northeast of Kulanaokuaiki Pali broke open and moved during the 1965 swarm. Similar, though smaller, episodes of ground breakage had occurred in 1960 and 1963, and another was to take place in 1975. In fact, this area, part of the Koa`e fault system, is one of the most active areas of faulting in the world. In the past 700 years or so, the Koa`e system has opened nearly 20 m (65 feet) in a north-south direction along a traverse that passes just west of the new campground. Along another traverse 2 km (1.2 miles) northeast of the first, the amount of opening is even greater, more than 30 m (100 feet).

The Koa`e fault system is part of the breakaway zone that, over long periods of time, separates Kilauea's mobile south flank from the rest of the volcano. Swarms of earthquakes and ground ruptures will recur for thousands of years to come, and the name of the new campground will remain pertinent.

Lava flows as well as shaking and cracking have impacted the area. The campground is located in a small kipuka. The older flow in the kipuka is more than 1,300 years old, and the younger surrounding the kipuka is about 700 years old. Both flows were erupted from the summit of Kilauea at times when lava flows could escape the caldera. The present caldera will have to fill up more before any lava erupted in it can reach the new campground, and there are several pali between that would have to be overtopped or run around. For those reasons, the campground seems rather safe from lava inundation for some time to come.

Between the two flows at the campground are several beds of volcanic ash and blocks. These layers were well exposed when the pit for the campground toilet was being dug. That is now off limits, but more layers can be seen by walking westward for 200 m (yards) or so to a place where little grass-covered mesas of ash stand above the older flow. Careful looking will find heavy gray rocks 3 cm (1 inch) or more in diameter lying on the surface of the older flow. These rocks rained from the sky during one or more powerful explosions before about A.D. 1000. Such explosions could happen again, though they are rarer events than lava flows.

Kulanaokuaiki campground is in a dynamic geologic setting. Enjoy!

Eruption Update

Eruptive activity of Kilauea Volcano continued unabated during the past week. Lava is erupting from Pu`u `O`o and flowing through a network of tubes toward the coast. Lava is visible at times on Pulama pali, and surface flows are active in the area between the Royal Gardens subdivision private access road and the sea coast. Lava is intermittently entering the ocean between Waha`ula and Kamokuna. The public is reminded that the ocean-entry areas are extremely hazardous, with explosions accompanying sudden collapses of the new land. The active lava flows are hot and have places with very thin crust. The steam clouds are highly acidic and laced with glass particles.

Residents in all districts of the Big Island were shaken by a magnitude-5.0 earthquake at 8:18 p.m. on Saturday, April 1. The large temblor was located 10.0 km (6 miles) southeast of the summit of Kilauea Volcano at a depth of 8.5 km (5.1 miles). The shaking did not affect the eruption at Pu`u `O`o, and, except for falling items, there were no reports of damages or injuries resulting from the earthquake.

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Updated: 10 Apr 2000